UNIX 6th Ed. - /usr/source/mdec/ht.s

   1: htcs1 = 172440
   2: htba  = 172444
   3: htfc  = 172446
   4: htcs2 = 172450
   5: htds  = 172452
   6: httc  = 172472
   7: 
   8: P800 = 1300
   9: P1600 = 2300
  10: PIP = 20000
  11: MOL = 10000
  12: ERR = 40000
  13: REV = 33
  14: READ = 71
  15: REW = 7
  16: 
  17: tread:
  18: 1:
  19:         mov     ba,mtma
  20:         cmp     mtapa,tapa
  21:         beq     1f
  22:         bhi     2f
  23:         jsr     pc,rrec
  24:         br      1b
  25: 2:
  26:         jsr     pc,rew
  27:         br      1b
  28: 1:
  29:         mov     wc,r1
  30: 1:
  31:         jsr     pc,rrec
  32:         add     $256.,r1
  33:         bmi     1b
  34:         rts     pc
  35: 
  36: rrec:
  37:         mov     $htds,r0
  38:         tstb    (r0)
  39:         bpl     rrec
  40:         bit     $PIP,(r0)
  41:         bne     rrec
  42:         bit     $MOL,(r0)
  43:         beq     rrec
  44:         mov     $htfc,r0
  45:         mov     $-512.,(r0)
  46:         mov     mtma,-(r0)
  47:         mov     $-256.,-(r0)
  48:         mov     $READ,-(r0)
  49: 1:
  50:         tstb    (r0)
  51:         bpl     1b
  52:         bit     $ERR,*$htds
  53:         bpl     1f
  54:         mov     $-1,*$htfc
  55:         mov     $REV,(r0)
  56:         br      rrec
  57: 1:
  58:         add     $512.,mtma
  59:         inc     mtapa
  60:         rts     pc
  61: 
  62: rew:
  63:         clr     *$htcs2
  64:         mov     $P800,*$httc
  65:         mov     $REW,*$htcs1
  66:         clr     mtapa
  67:         rts     pc
  68: 
  69: mtapa:  0
  70: mtma:   0

Defined functions